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Discussion Starter #1
Hi, I have a few questions about my car, I have a reccuring bucking problem that does seem to get less intense when I clean the maf but something else is wrong.

I had the car connected to a computer to see what was wrong and 2 things came out.

First, the maf is close to be dead, and will be replaced.
The rear o2 sensor gives the same reading when connected or disconnected.

There is also a noise coming from the engine which I believe would be the upper chain tensionner. Would a worn out tensionner cause timing issues?

I'm asking cause I did almost all that was suggested to fix my issue but the car still bucks, there is no error code as such given by the computer but still it's barely drivable sometimes(50km/h at 5th gear).

And again, it only happens when hot.

Thanks in advance, your answers did help in the past


John
 

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If your MAF is close to dying, it can cause all kinds of problems from low revs (less than 2000 rpms) to random and miscellaneous fuel consumption and air flow readings causing your engine to misfire and have all kinds of nervous breakdowns. As for your rear O2 sensor, it is basically useless other than to plug the hole you would have in your exhaust piping. It is used to extend the life of your catalytic converter, and the car performs perfectly with it unplugged. I have a '95 GA16DE dropped in a '90 Sentra, and have never had the rear O2 sensor even installed on the car and no problems at all.

As for the tensioner, your timing chain tensioners (both upper and lower) as well as your timing chain guides might need replacing. I would start with the upper tensioner, it is much easier to get to than the rest. Also, check your oil level. Back when my front main seal was bad and my engine leaked oil, my timing chain sometimes rattled because it was under-oiled. Your timing chain, if it is jumping timing due to no tensioner, can also cause bucking.
 

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Discussion Starter #3
Ok, I replaced the MAF today but it still bucks. Readings with my meter are within specs according to the manual so I guess that's one thing less to worry about but still.

Anything else could cause that, I'll replace the tensionner later this week but I'm confused cause it only bucks when the engine is hot and only when I'm giving gas, like let's say i'm going at 3700rpm and it bucks constantly, as soon as I release the pedal, it stops.

I need help, desperately,

Thanks
John
 

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Discussion Starter #4
weeeell, I changed the tensionner today, no more tractor noises from the engine. It was extremely worn out, close to break in fact. The only problem I have is that it still bucks, again. I noticed that the lower cogwheel was somehow worn but with the new tensionner it should still be plenty.

After changing the maf and the upper tensioner I'm still needing help. What can be the cause of all my troubles, I'd like to have ideas of what can cause bucking/misfiring/jerking and not give an error code.
 

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I'm not much of a Nissan Guy yet but I would look into the possibility of may the timing jumped? Have you checked it with an inductive light??
 

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Discussion Starter #6
Not yet no, but would timing be an issue only when the engine is hot?

I'm also trying to get info about the catalytic converter, could that be an issue? I mean, the rear o2 sensor does give the same reading when connected and disconnected.

I don't feel like changing every piece on my car but it must be something. I've read in the forums that some people never found out what was causing the issue...

Like I said, the car misfires only when accelerating, only when hot, not always at the same rpm and it seems to be worst when it's hot outside.

MAF, IACV, Tensionner, hoses were tested and changed when needed, there is no error code and nothing else is wrong according to the car's computer.

Can't be that many things can it ?
 

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I have this kind of problem with my gf's GA16i.It bucks only when it's hot, kind of like misfiring.I have changed a million things in her car.What left to suspect is the fuel pump,fuel injector or faulty idle air control valve/temperature sensor.Both IACV and temp sensor are new,but I feel like the temp sensor is just not doing its job.Idle isn't stable when it's cold,and heat up really slowly.

Or it can be the plug wires.The wires are from shucks.Maybe that's why.

If it's on throttle it doesn't buck.I still don't think it's fuel issue.I am not sure...
 
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